I'm in England, although it's difficult to say what my effective timezone is.
It won't work in everything, but it will work in some other things.
[quote]If I have 3 folders which I do not want to include, I guess the following would be the filter string if the folders were named Trip1_Jan, Trip2_Feb, and Trip3_Mar, and they were the only folders whose name started with "Trip".
~Trip*.*[/quote]
You may need brackets, and you should not include the .* as the folder names do not have dots or extensions in them.
So this is what you could use:
~(Trip*)
Using that as a filter in Flat View may have unwanted effects, though. It will also filter out any files with names like Trip01.jpg
You'd be better off using
~(Trip1_Jan|Trip2_Feb|Trip3_Mar)
That is safer, since you're unlikely to have files called any of those three names.
[quote]And, as you noted, to include these 3 extensions, it would be
*.(txt|doc|jpg)
To exclude then
~*.(txt|doc|jpg)[/quote]
You probably need the extra brackets again:
~(*.(txt|doc|jpg))
That gets quite difficult if you're trying to do that in a single wildcard expression.
To do complex filtering, filtering some things in and other things out, I would use the Find tool (Tools -> Find Panel) instead of trying to use filtering and Flat View. With the Find tool you can break things down and create complex rules much more easily.